The Common Weld Quality System

00:04:18
https://www.youtube.com/watch?v=kl8TAVdvE48

概要

TLDRResistance spot welding is a method used to join metal pieces through a combination of pressure and heat. This process involves placing the pieces together at a faying surface where a controlled electrical current is applied through copper electrodes, generating heat due to electrical resistance. Key variables include current, time (squeeze, weld, hold), and squeeze force, which are crucial for achieving quality welds. Proper manipulation of these factors ensures adequate heat production—too much can cause melting, while too little leads to weak joints. Specific settings depend on the material type and thickness, ensuring consistent and reliable results. Testing and guidelines such as the ws4 specification provide necessary parameters for effective operation.

収穫

  • 🔌 Resistance spot welding joins metals using heat and pressure.
  • ⚡ Heat is generated through electrical resistance at the faying surface.
  • ⏱️ Key time intervals: squeeze, weld, and hold time are essential.
  • ♨️ Too much heat leads to melting; too little results in cold welds.
  • 📏 Squeeze force impacts heat production significantly.
  • 📈 Increasing squeeze force reduces weld heat; decreasing increases it.
  • 🚫 Improper squeeze force can cause molten metal expulsion.
  • 📖 Correct parameters are found in the ws4 specification for consistency.
  • 🔧 Settings vary by material type and thickness for effective welding.

タイムライン

  • 00:00:00 - 00:04:18

    Resistance spot welding joins metal pieces using heat and pressure. It involves applying a squeeze force while passing a low voltage, high amperage electrical current through copper electrodes. This current encounters resistance at the faying surface, generating heat to form a weld nugget. Proper heat control is crucial; too much heat causes metal to melt and eject, while too little results in a cold weld. The heat regulation is managed by adjusting three variables: current, time, and squeeze force. Current, measured in amperes, significantly influences heat levels. Time is expressed in cycles, with essential intervals being squeeze time (creating contact), weld time (current flow), and hold time (cooling). Squeeze force affects contact; higher force reduces weld heat, while lower force increases it. Specific parameters for force, weld current, and time are essential for effective spot welding, as detailed in the ws4 specification.

マインドマップ

ビデオQ&A

  • What is resistance spot welding?

    A method of joining two or more pieces of metal using heat generated by electrical resistance and applied pressure.

  • What creates the heat in resistance spot welding?

    The heat is generated from the electrical resistance of the workpiece at the faying surface during current flow.

  • What are the key parameters affecting weld quality?

    Current, time (squeeze time, weld time, hold time), and squeeze force.

  • What is the consequence of too much heat during welding?

    It can cause the metal to melt and produce a flash, leading to poor weld quality.

  • What happens if there's not enough heat?

    It results in a cold weld, which is undersized or may not form at all.

  • How is weld time measured?

    In cycles, based on the frequency of alternating currents (e.g., 60 cycles per second in North America).

  • What is squeeze force?

    The pressure applied by the electrodes to bring the surfaces of the parts closer for effective welding.

  • How does squeeze force affect heat production?

    Increasing force reduces resistance, generating less heat, while decreasing force increases resistance, generating more heat.

  • What can happen with improper squeeze force settings?

    It can lead to more heat at the electrode tip than at the faying surface, resulting in surface expulsion of molten metal.

  • Where can one find the correct weld parameters?

    The ws4 specification contains the correct force parameters, weld time, and current values.

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  • 00:00:04
    resistance spot welding is a method of
  • 00:00:06
    joining two or more pieces of metal
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    using a precisely controlled combination
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    of pressure and heat resistant spot
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    welds are formed by heating a spot of
  • 00:00:16
    metal electrically while applying
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    pressure in the form of squeeze Force
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    the heat brings the metal to a plastic
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    State and the pressure pushes the heated
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    metal from the two surfaces together
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    creating a weld nugget that joins the
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    two pie pie the heat for this weld is
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    Created from the electrical resistance
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    of the workpiece hence the name
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    resistance spot
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    welding here is how the process works
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    the parts to be joined are placed
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    together where the two parts meet is
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    called the faying surface this is where
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    the weld will be formed the two copper
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    electrodes of the weld gun are brought
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    together on either side of the joined
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    Parts they press together squeezing the
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    parts between them with great force
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    while the parts are held together a low
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    voltage High amperage electric current
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    is passed between the
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    electrodes as this current passes
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    through the pieces to be joined it
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    encounters resistance producing
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    heat electrical resistance is greatest
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    at the faying surface where the pieces
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    of metal meet so that is where the most
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    heat is generally produced this is where
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    the weld nugget forms to make a good
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    weld it is imperative that the right
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    amount of heat be produced
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    if there is too much heat the metal will
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    melt and eject from The Joint producing
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    a flash if there is not enough heat the
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    weld will be undersized or will not form
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    at all and this is what we call a cold
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    weld in order to regulate weld heat
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    there are three variables that can be
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    manipulated current time and squeeze
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    Force current is measured in ampir
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    changing this value will have a profound
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    effect on the amount of heat in a weld
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    time in resistance spot welding is
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    expressed in Cycles Cycles are units
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    based on the frequency of alternating
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    currents in North America current is
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    provided at 60 cycles per second so six
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    Cycles is equal to 1/10 of a
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    second there are three time intervals
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    which are essential to resistance spot
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    welding squeeze time the time interval
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    during which the electrode tips close
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    and press the material together to
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    create a positive contact between the
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    top piece and the bottom piece weld time
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    the time during which the electrical
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    current is actually flowing through the
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    closed electrode tips and hold time the
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    time during which the electrode tips
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    remain closed after the weld current has
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    ceased allowing the weld nugget to cool
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    and
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    solidify adjusting the weld time gives
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    us much finer control over the amount of
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    wed heat than does adjusting the
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    current squeeze force in resistance spot
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    welding Works differently than you might
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    expect by increasing the force you are
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    bringing the surfaces of the parts into
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    closer contact this reduces the
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    resistance level in the metal stack and
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    causes less weld heat to be produced in
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    the opposite situation reducing squeeze
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    Force increases the tiny separation
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    between the parts to be welded this
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    increases resistance and results in more
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    weld heat in an extreme case of low
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    Force resistance might actually be
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    greater between the electrode and the
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    part than between the parts being welded
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    this must be avoided because it can
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    result in more heat being generated at
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    the electrode tip than at the material
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    faying surface this could cause a
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    surface expulsion in which molten metal
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    can be thrown off in any
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    direction at General Motors we use a
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    specific squeeze for setting which is
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    dependent on material type and thickness
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    this value is a critical requirement for
  • 00:04:04
    consistency in spot
  • 00:04:07
    welding you can find correct Force
  • 00:04:09
    parameters along with weld time and weld
  • 00:04:12
    current values in the ws4 specification
タグ
  • Resistance Spot Welding
  • Metal Joining
  • Electrical Resistance
  • Weld Nugget
  • Heat Generation
  • Squeeze Force
  • Weld Quality
  • Welding Parameters
  • Material Thickness
  • ws4 Specification